E30 Zone

i filled my 318i coupe up a few weeks ago and i noticed the fuel seems to be leaking out of the tank on the top where the sender (i think) is - under the inspection hole under the rear seats.

i want to get this sorted cos i still get fuel smell inside the car even though i am only putting in 15 quid at a time.

every now and then i still get the smell inside the car.

i would like to know what i should be looking out for - some one said the expansion bottle, but what about it? where is it, and what pipe work should there be?

i know the filler neck was dry so not leaking from there.

i'm having the same problem as you if i fill up over half way, itleaks from the tank onto the floor and i also noticed there is sometimes a little fuel coming from the fuel line into the engine witch is the smell what you can smell inside your car, i would love to no the answer to this then i could sort mine out to

The braided vent hose can rot/perish and leak fuel on top of the tank, have you checked the filler stub on the tank? This is the first job and a very common rust area

anyone else?

i'm pretty sure my filler stub is ok too.

So are you saying that you are still getting a fuel smell even after having sorted the leak on top of the tank ?

If you haven't replaced the o ring on the sender unit I wouldn't go looking for more leaks yet as smell is one of the best ways to trace petrol leaks.

The expansion bottle is in the right rear arch, above a plastic cover.

I have a leak in this area where the vent hose meets the filler neck, means I get a strong fuel smell around the arch area if I fill the tank.

The schematic for the pipes is like this (assuming you don't have the auxiliary fuel tank in the boot):

i've not taken the sender out from the top of the tank for the simpple reason i have not known what to be looking out for. i'll have a look for the exp tank after work and see whats what...

I take it you have checked the pressure hose from the fuel pump? Its not likely to be the O ring if you are only putting in £15 worth of juice at a time

i just took some parts off - the braided hose is real poorly i think - real soft and doesnt 'spring back' when squeezed.

if it is that pipe, whast the internal diameter of it?

Have you checked the rubber hoses in the engine bay ? If the ones at the fuel tank end are shot it stands a chance that the ones that have suffered underbonnet conditions for 20 Years will be past their best - and a common cause of fuel smells.

the pipes themselves seem to be ok. i did check them earlier and one connection needed tightening as it was seeping petrol - possible smell in the car. i'll give it a good drive tomoz and see how it goes.

bump

Lets start at the begining.....
Petrol is nasty stuff and will leak from the tinyest hole.
So check all flexible hoses and replace any that look suspisious,fuel hose is cheap by the metre from a motor factor.
Fuel tanks will leak because of rust damage,this is mostly around the filler stub.To check,slide under the car on the driver's side just forward of the rear wheel and locate the entry point to the tank,there's a rubber connecting hose there,grab it and pull,if it comes away in your mitt,or wobbles about,that's your leak point!
On top of the tank,accessable via two handy hatches under the rear seat,are the pump and the two gauge sender units,these both have large 'O' ring seals that can perish and cause leaks.
Also under the driver's side hatch where the fuel pump lives is the main tank breather that goes to the expansion tank that hides high up under the r/h rear wing,this fabric covered pipe has a nasty habit of rotting and/or splitting at it's joining point to the tank,causing petrol to spill out as the car is filled.
Only really difficult bit is swapping a rusty tank,rest is easy to get at and cheap to fix.

any idea what the diameter of the pipe is that connects the tank to the exp bottle?

Hang on, firstly you ask what is the diameter of the braided pipe (the answer is 14 x 20), then you ask for the diameter of the pipe which goes from the tank to the expansion bottle... the braided pipe does not do this. See the diagram I posted before.

The braided pipe goes from the tank breather to a stub on the filler neck. The only pipe which goes from the tank to the expansion bottle is the pipe which feeds the content of the bottle back to the tank and this is 8 x 13 at the ends, with a smaller section of pipe in the middle.

This is all data for MY CAR taken from realOEM with the chassis number, I suggest you do the same with your chassis no as there are many variations depending on pre / post, type of tank, country spec etc.

clipper wrote:Hang on, firstly you ask what is the diameter of the braided pipe (the answer is 14 x 20), then you ask for the diameter of the pipe which goes from the tank to the expansion bottle... the braided pipe does not do this. See the diagram I posted before.

The braided pipe goes from the tank breather to a stub on the filler neck. The only pipe which goes from the tank to the expansion bottle is the pipe which feeds the content of the bottle back to the tank and this is 8 x 13 at the ends, with a smaller section of pipe in the middle.

This is all data for MY CAR taken from realOEM with the chassis number, I suggest you do the same with your chassis no as there are many variations depending on pre / post, type of tank, country spec etc.

thanks for the info and appologies for the confusion on my part - happens alot!

i'm gonna change the braided hose tonight if i can get some pipe from the local hydraulic supplies and take it from there.

Just out of interest... what would happen if the braided hose was blocked up at both ends and just not used?

Hydraulic hose is not suitable for petrol and will perish very quickly, you can buy the braided hose from the dealer, its about £12
Before you check for leaks on the supply/return bridge the relay so the system is under pressure

i got some propper unleaded fuel line.